JPH07237283A - Laminated polyester film to be transferred simultaneously with molding - Google Patents

Abstract

PURPOSE:To obtain a laminated polyester film to be transferred simultaneously with molding, having superior moldability, heat resistance, and surface properties and having a uniform thickness by a method wherein polyester layers forming a laminated film of two or more layers respectively have a specific surface orienting degree, and one of the layers has a specific thickness ratio to the total thickness. CONSTITUTION:A biaxially oriented thermally fixed laminated film made of at least two layers contains a polyester A layer and a polyester B layer. The polyester A layer has a surface orienting degree DELTA PA equal to or more than 0.100. The polyester B layer has a surface orienting degree DELTAPB less than 0.100. The thickness of the polyester A layer is less than 50% of the total thickness. It is preferable that the polyester A layer has a multi-layer structure differing in copolymer component or blend component and forms each exposed surface of the film. It is preferable that the polyester B layer is made of an amorphous polyester.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated polyester film for simultaneous molding and transfer, which has excellent moldability, heat resistance and thickness uniformity, and also has excellent surface properties. More specifically, the present invention relates to a laminated polyester film for deep drawing simultaneous transfer having a high drawing ratio.

[0002]

2. Description of the Related Art In recent years, the application of polyester to molding applications has been attracting attention. Particularly, as a printing method for molded articles, transfer printing is performed simultaneously with molding, that is, so-called simultaneous molding. Transfer methods are becoming popular. As a film suitable for such a purpose, a biaxially stretched polyester film copolymerized with isophthalic acid or the like has been used.

However, as the drawing height at the time of molding has become higher and higher, a higher level of molding transfer such as a grid pattern has been required. With the current film, the moldability and heat resistance (dimensional stability) are improved. ) Have been found to be impossible to satisfy at the same time. In particular, with the demand for larger size and higher drawing height for molding applications such as refrigerators and automobiles, improvement of the film has been strongly desired.

[0004]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventor has conducted diligent studies and, as a result, has a specific laminated structure, whereby the moldability and the heat resistance (dimensional stability) can be simultaneously achieved. As a result, they have completed the present invention. That is, the gist of the present invention consists of a biaxially stretched heat-fixing laminated film of at least two layers including a polyester A layer and a polyester B layer, and the plane orientation degree ΔP _A of the polyester A layer is represented by the following formula: Surface orientation Δ
A laminated polyester film for simultaneous molding transfer, wherein P _B satisfies the following expression and the ratio of the polyester A layer to the total thickness is less than 50%.

[0005]

[Formula 2] ΔP _A ≧ 0.100 ・ ・ ・ ・ ・ ΔP _B <0.100 ・ ・ ・ ・ ・

The present invention will be described in detail below. The laminated film of the present invention is a biaxially stretched heat-setting film having a multi-layer structure including at least a polyester A layer and a polyester B layer, and a release layer and a printing layer are formed on the film for simultaneous molding transfer. Used.

First, the polyester A layer will be described. The polyester A constituting the polyester A layer may be of any structure as long as the film has a ΔP _A of 0.100 or more after the biaxially stretched and heat-set, but a polyester substantially composed of a homopolymer is used. As a representative one.

Such a polyester is obtained by polycondensing an aromatic dicarboxylic acid and an aliphatic glycol. Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid and naphthalene-2,6-dicarboxylic acid, and examples of the aliphatic glycol include ethylene glycol and
Diethylene glycol, tetramethylene glycol, neopentyl glycol, 1,4-cyclohexane dimethanol and the like can be mentioned.

Examples of typical polymers include polyethylene terephthalate (PET), polyethylene-2,6-naphthalene dicarboxylate (PEN) and polycyclohexane dimethylene terephthalate copolymer (PCT). In addition to the above-mentioned polymers, the polyester A further contains other aromatics and / or other aromatics at a ratio such that ΔP _A after heat setting is not less than 0.100, specifically, 10 mol or less, preferably 15 mol% or less. Alternatively, it may be a copolymerized polymer obtained by copolymerizing a dicarboxylic acid diol of a fatty acid. The copolymerization component may be the same as that described for polyester B below.

The polyester A constituting the polyester A layer may be a blend with another polymer. Examples of other polymers include polyamides, polyolefins, and polycarbonates, which may be blended within a range that does not extremely reduce the crystallinity of the polyester A or extremely increase the surface roughness. The blending ratio is usually 15% by weight or less, preferably 5% by weight or less.

The polyester A layer may have the same composition throughout, but it is also preferable that the polyester A layer is a multilayer having different copolymerization components or blending components as long as the formula is satisfied. In the present invention, it is preferable to configure both surfaces of the film where the polyester A layer is exposed. Of course, the layer A may constitute layers other than these front and back.

Degree of plane orientation ΔP of polyester A layer_AIs
It is 0.100 or more. ΔP_AIs less than 0.100,
Heat resistance and flatness cannot be maintained, which is inappropriate. ΔP_AIs good
It is preferably 0.130 or more, more preferably 0.150.
That is all. Next, the polyester B layer will be described.
It Polyester B layer plane orientation degree ΔP _BIs 0.100
I'm full. ΔP_BIs 0.100 or more, the moldability is poor.
Is inappropriate. ΔP_BIs preferably 0.050 or less,
It is more preferably 0.030 or less, and particularly preferably 0.
It is 010 or less.

The polyester B constituting the polyester B layer is preferably a substantially amorphous polyester. As the method for amorphizing the polyester B, the polyester B has a melting point lower than the heat setting temperature after biaxial stretching, and therefore, a method of amorphizing at the time of heat setting is preferable. Examples of such a low-melting point polyester include polyesters composed of the same components as the polyester A constituting the polyester A layer, but also polyesters copolymerized with other acid component or glycol component. Polyester A layer and B
The acid component and the glycol component of the polyester constituting the layer need not be the same, but are preferably the same.

The acid component and the glycol component need not be the same, but are preferably the same. B
As the copolymerization component of the polyester B constituting the layer, terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, diphenylsulfodicarboxylic acid, diphenyletherdicarboxylic acid, diphenoxyethanedicarboxylic acid, cyclohexane are used as the dicarboxylic acid different from the main component. Dicarboxylic acid, diphenyldicarboxylic acid, diphenylthioether dicarboxylic acid, diphenylketone dicarboxylic acid, phenylindanedicarboxylic acid, sebacic acid, euic acid, dodecanedicarboxylic acid, dimer acid, aromatic dicarboxylic acid having metal sulfonate, polyether dicarboxylic acid, etc. Among these, among these, those selected from isophthalic acid, naphthalenedicarboxylic acid, sebacic acid, and aromatic dicarboxylic acid having a metal sulfonate are preferable. .

On the other hand, as the glycol component different from the main component, ethylene glycol, propylene glycol, tetramethylene glycol, cyclohexanedimethanol, 2,2, -bis (4-hydroxydiphenyl) propane, 2,2-bis (4-) Examples thereof include hydroxyphenyl) propane, bis (4-hydroxyphenyl) sulfone, jetylene glycol, neopentyl glycol, hydroquinone, cyclohexanediol, and polyalkylene glycol. Among these, tetramethylene glycol, cyclohexanedimethanol, neopentyl. Those selected from glycols and polyalkylene glycols are preferred.

The laminated film of the present invention comprises polyester A
It is composed of a biaxially stretched heat-fixing laminated film having a multilayer structure including a layer and a B layer. The multilayer structure is a two-layer structure of A / B layer, A / B
The structure may be a 3-layer structure of / A, a 5-layer structure of A / B / A / B / A, or the like. Alternatively, the A layer and the B layer may be multi-layered to form a laminated structure such as A ₁ / A ₂ / B ₁ / B ₂ / B ₁ / A ₂ / A ₁ . Among the above structures, A / B / A,
The structure of A / B / A / B / A is preferable including the aspect of installation of the manufacturing apparatus.

In the laminated film of the present invention, the polyester A layer has a thickness of more than 0.1 μm and less than 20 μm,
Furthermore, more than 0.5 μm and less than 10 μm, especially 1 μm
More than 5 μm is preferable. When the thickness of the polyester A layer is 0.1 μm or less, heat resistance, dimensional stability, and surface properties tend to be poor, while when it is 20 μm or more, moldability may be poor.

The thickness of the polyester A layer must be less than 50% of the total film thickness, even 2
It is preferably 5% or less, and particularly preferably 2 to 10%. When the thickness of the polyester A layer exceeds 50% of the total film thickness, the improvement in moldability is insufficient. The total thickness of the laminated film is usually 5 to 500 μm, preferably 5 to 300 μm.
μm, more preferably 15 to 75 μm, and particularly preferably 25 to 60 μm.

Further, in order to improve the slipperiness of the film, it is preferable that fine particles such as an organic lubricant and an inorganic lubricant are contained only in the A layer or in the A layer and the B layer. For example, A
In the / B / A three-layer film, it is desirable that fine particles be contained in the A layer and that the B layer be made of recycled or inexpensive resin. In addition, the A layer and / or the B layer may contain additives such as a stabilizer, a colorant, an antioxidant, an antifoaming agent, and an antistatic agent, if necessary.

The fine particles imparting lubricity include kaolin, clay, various calcium carbonates, silicon oxide, calcium terephthalate, aluminum oxides such as α-, γ, -δ-, and θ-, titanium oxide, calcium phosphate, fluorinated. Known inert external particles such as lithium and carbon black,
Depending on the high melting point organic compound, monodispersed spherical organic particles, crushed organic particles, crosslinked polymer and metal compound catalyst used in polyester synthesis, such as an alkali metal compound or an alkaline earth metal compound, which are insoluble during melt film formation of polyester resin Examples include internal particles formed inside the polymer during polyester production. The content of fine particles contained in the film is usually 0.002 to 2.0% by weight.
And the average particle diameter is preferably in the range of 0.001 to 3.5 μm.

The polyester of the present invention has an intrinsic viscosity in a film of preferably 0.50 or more, more preferably 0.60 or more. The intrinsic viscosity of the film is 0.5
If it is less than 0, sufficient strength and moldability may not be obtained. In the laminated film as in the present invention, as long as the above range is satisfied, the A layer and the B layer may have the same intrinsic viscosity or different viscosities. Further, the viscosity of the A layer may be higher or lower than that of the B layer.

In the film of the present invention, an atmosphere of 150 ° C.
Film strength F at 100% elongation in the air₁₀₀Is
1.0 kg / cm²It is preferably less than. The present invention
F in₁₀₀Is the fiber at 100% elongation at 150 ° C.
It is the average value of the strength of the lum in the vertical and horizontal directions. F₁₀₀value
Is preferably more than 0 and 1.0 kg / cm ²Range less than,
Particularly preferably 0.1 kg / cm²1.0 kg / c or more
m²Is less than. According to our examination results, the strength F₁₀₀
The value is closely related to the formability of the film,₁₀₀But
1.0 kg / cm²If the film exceeds, the moldability is low.
And tends to be inferior in deep drawability. Also in the film longitudinal direction
Of the film strength at 150 ° C and 100% elongation in the transverse direction
The difference is usually 2 kg / cm²Below, preferably 1k
g / cm²Below, more preferably 0.5 kg / cm²
It is the following. This difference is 2kg / cm²Beyond is anisotropic
The shape becomes too large and the moldability deteriorates, and the pattern is distorted
May occur.

In the film of the present invention, the thickness unevenness of the film is preferably less than 30%, more preferably less than 20%, and particularly less than 15%. 30 such uneven thickness
If it is more than 0.1%, the elongation of the film during molding becomes non-uniform, and the pattern tends to be distorted during molding transfer.

Regarding the shrinkage properties of the film of the present invention,
It is preferable that both the longitudinal and lateral shrinkages after treatment at 150 ° C. for 3 minutes are less than 40%. In the case of a film having a longitudinal or lateral shrinkage of 4.0% or more, the shrinkage of the film becomes too large in the heating section during the processing step, which may make it difficult to correct the design. The shrinkage ratio is preferably 2.0%, more preferably 1.0%.

Next, a method for producing the laminated film of the present invention will be described. As a method for obtaining the laminated film, a known method such as a coextrusion method or a dry lamination method is used, and the coextrusion method is particularly preferable from the viewpoint of productivity. Therefore, the film forming method by the coextrusion method will be described below as a representative.

First, chips of several kinds of polyester containing an appropriate amount of inorganic fine particles and the like are dried, and then blended so as to have a required composition to prepare the polyester required for each layer. This polyester is melted at a temperature of 200 to 320 ° C. by using different extruders, merged in a pipe or a die and extruded into multiple layers, and then rapidly cooled on a casting drum to obtain an unstretched laminated sheet having a required structure. obtain. A popper dryer, a paddle dryer, a vacuum dryer, etc. can be used for drying the polyester chips. The extrusion method is preferably a T-die method. At the time of extrusion, the thickness ratio of each layer of the laminated film can be appropriately adjusted by adjusting the discharge amount by the gear pump of each extruder. Further, when casting, a so-called electrostatic contact method is used, so that a laminated sheet with less unevenness in thickness can be obtained.

The unstretched laminated sheet obtained is continuously rolled.
In the stretching process, Tg^min-10 ° C or higher Tc^max-10
It is stretched 2.0 times or more in both the longitudinal and transverse directions in the temperature range of ℃ or less.
Tg here^minIs the Tg of the raw material polyester used (glass
Minimum value of transition concentration, Tc ^maxIs the raw material used
It represents the maximum value of Tc (crystallization temperature) of Stell. Biaxial stretching
In the subsequent heat setting process, the laminated film is
At a temperature higher than the melting point and lower than the melting point of the layer A −10 ° C.
Heat set. Heat setting is generally performed under emergency fixing.
Provided, but during heat setting and / or cooling after heat setting
20% in the longitudinal and / or transverse direction of the film
You can also relax and stretch.

During or after the stretching step, a coating layer is formed on one side or both sides of the film, corona treatment or the like in order to impart adhesiveness, antistatic property, slip property, releasing property to the film. You may perform the electric discharge process of. In particular, it is preferable to provide the release layer with an intein coat.

Here, in the above-mentioned laminated film, as a typical polyester composition, the A layer is composed of polyethylene terephthalate or a high melting point polyethylene terephthalate copolymer having crystallinity and the B layer is composed of a low melting point polyester copolymer. It is what is done. However,
It is preferable that the A layer is a film having a higher Tg in order to impart heat resistance of the film and non-tackiness at the time of manufacturing and molding the film. One example thereof is poly-1,4-cyclohexanedimethyl terephthalate and a copolymer thereof (PCT), and particularly preferable one is polyethylene-2,6-naphthalate or a copolymer thereof which maintains a high melting point. . Polyethylene-2,6
Since naphthalate has a Tg as high as 40 to 45 ° C. as compared with polyethylene terephthalate, it is preferable because problems such as film sticking during film production and molding can be solved all at once.

[0030]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples as long as the gist thereof is not exceeded. The evaluation method of the film is as follows.

(1) F ₁₀₀ (kg / mm ² ): 150 ° C.
Film strength at 100% elongation under atmosphere Intesco 20 tensile tester with constant temperature chamber
A 01-type thermostat was set at 150 ° C., a film having a width of 15 mm was set to have a chuck distance of 50 mm, and the film was allowed to stand for 2 minutes. Then, the strength at 100% elongation was measured at a tensile speed of 200 mm / min. The measurement was performed in the machine direction and the transverse direction of the film, and the average value was defined as F ₁₀₀ .

(2) Unevenness of film thickness A continuous film thickness measuring device (using an electronic micrometer) manufactured by Anritsu Denki Co., Ltd. was used to measure the film thickness of 5 m along the longitudinal direction of the film. Was calculated.

Thickness unevenness = (maximum thickness of film−minimum thickness of film) × 100 / average thickness of film (3) Degree of plane orientation of film (ΔP) The refractive index of the film is measured by Atsube manufactured by Atago Co., Ltd. Using a meter, using a sodium lamp as the light source,
ΔP was calculated from the following formula.

## EQU3 ## ΔP = 1/2 (η _r + η _p ) −η _d (where, η _r , η _p, and η _d are the maximum refractive index in the film plane and the refraction in the film plane orthogonal thereto, respectively) When it is not possible to directly measure with a laminated film, which represents the refractive index and the refractive index in the thickness direction, a single layer sample was made as a model and measured.

(4) Intrinsic viscosity ([η]) 0.2 g of a sample was added to phenol / tetrachloroethane = 50
The mixture was added to 20 ml of a mixed solvent of / 50, heated at about 110 ° C. for 30 minutes, and then measured at 30 ° C.

(5) Heat shrinkage rate (%) of the film A film having a length of 10 cm was shrunk for 3 minutes in an unloaded state during a guard open at a temperature of 150 ± 2 ° C., and heat shrinkage in the machine direction and the transverse direction. The rate was calculated according to the following formula.

## EQU00004 ## Heat shrinkage ratio = (10-l) .times.100 / 10 (wherein, 1 is the film length after shrinkage (cm) in the above formula)
Indicates)

(6) Formability as Transfer Film Using a mold having a length and width of 10 cm shown in FIG. 1 and a maximum depth of 3.0 cm, the film was preformed inside the mold by vacuum and piezoelectric and then heated. Molding was performed by injecting a resin. The formability of the film was evaluated as follows according to the frequency of breakage of the film after forming. ⊚: No film breakage ○: Almost no film breakage Δ: Film breakage occasionally occurs ×: Film breakage occurs frequently

(7) Suitability as transfer film After forming a layer composed of a release layer, a printing layer and an adhesive layer on the film, molding transfer was actually continuously carried out by the method of (6). There is no breakage of the film during molding and can be operated continuously,
In addition, when the pattern was not distorted or the printing was not printed in the printing on the molded product, it was evaluated as ◯, and when not, it was evaluated as x.

The raw material polyesters used in the examples are shown below. Polyester A ₁ : Polyethylene terephthalate ([η] = 0.63) containing 500 ppm of amorphous silica particles having an average particle size of 1.0 μm Polyester A ₂ : Polyethylene-2 containing 550 ppm of amorphous silica particles having an average particle size of 1.2 μm , 6-naphthalate ([η] = 0.60)

Polyester B ₁ : 80 mol% of terephthalic acid as an acid component, 20 mol% of isophthalic acid, 98 mol% of ethylene glycol as a glycol component, and 2 mol% of diethylene glycol prepared by a conventional method (PET copolymer). Polymer) ([η] = 0.
69) Polyester B _1: 80 mole% 2,6-naphthalenedicarboxylic acid as acid components, 20 mol% of isophthalic acid, ethylene glycol 98 mol% as glycol components, consisting of diethylene glycol 2 mol%, the polyester copolymer was prepared in a conventional manner heavy Combined (PEN copolymer) ([η] =
0.61)

Example 1 Polyester A₁, Polyester B₁Of each chip
Polyester A after drying according to₁In extruder 1,
Polyester B₁Was melted in the extruder 2 at 280 ° C.
After that, polyester A₁Can be divided into 2 layers and coextruded into 3 layers
A through a die with a unique base₁/ B₁/ A₁Two kinds of
Co-extruded in 3 layers and quenched on casting drum
Then, an unstretched laminated sheet was obtained. At this time, close contact with the drum
The electrostatic contact method was used to improve the properties. Then 83 ° C
Stretched 3.6 times in the machine direction and 3.7 times in the transverse direction at 100 ° C
After that, heat set at 225 ° C. for 5 seconds to remove the 50 μm thick film.
An axially stretched laminated film was obtained. A ₁/ B₁/ A₁Of each layer
The thickness was 2 μm / 46 μm / 2 μm.

[0041] The polyester A ₂ instead of Example 2 Polyester A _1, the polyester B ₂ used in place of the polyester B _1, 3.8 times in the longitudinal direction at 135 ° C. The stretching conditions, also in the transverse direction at 135 ° C. A film having a thickness of 50 μm was obtained in the same manner as in Example 1 except that the film was stretched and then heat-treated at 235 ° C. for 5 seconds.

Comparative Example 1 A film having a thickness of 50 μm was obtained in the same manner as in Example 1 except that the polyester A ₁ was formed into a single layer.

Comparative Example 2 A film having a thickness of 50 μm was obtained in the same manner as in Example 2 except that the polyester A ₂ was formed into a single layer. The evaluation of these samples is shown in Table 1 below. From these results, it can be seen that the laminated film of the present invention satisfies the required quality and is remarkably excellent as a molded film.

[0044]

[Table 1]

[0045]

The film of the present invention has excellent moldability, heat resistance, thickness uniformity, surface property, etc., and is useful as a film for simultaneous molding transfer, and the engineering value of the present invention is high.

Claims (4)

[Claims] 1. A biaxially stretched heat-fixing laminated film comprising at least two layers including a polyester A layer and a polyester B layer, wherein the polyester A layer has a plane orientation degree ΔP _A expressed by the following formula. ΔP _B satisfies the following formula, and the ratio of the polyester A layer to the total thickness is less than 50%, a laminated polyester film for simultaneous molding transfer. [Formula 1] ΔP _A ≧ 0.100 ・ ・ ・ ・ ・ ΔP _B <0.100 ・ ・ ・ ・ ・ 2. The laminated polyester film for simultaneous molding transfer according to claim 1, wherein the laminated polyester film comprises at least three layers, and each layer constituting the exposed surface is a polyester A layer. 3. The laminated polyester film for simultaneous molding transfer according to claim 1 or 2, wherein the polyester A layer is a film mainly composed of polyethylene-2,6-naphthalate or a copolymer thereof. 4. Tensile strength F at 100% elongation at 150 ° C.
Forming laminated polyester film for simultaneous transfer according to any one of claims 1 to 3, wherein the ₁₀₀ is less than 1.0 kg / cm ^2.